Refraction occurs when waves travel from one transparent medium to another, causing a change in wave speed and direction.

The normal is an imaginary line drawn at 90° to a surface.

The angle of incidence is the angle between the incident ray and the normal.

The angle of refraction is the angle between the refracted ray and the normal.

Wavefronts are lines drawn to represent the peaks of a wave.

Refraction through a rectangular block (including wave front diagrams)

Physics

In A-level physics, some pupils will build on this knowledge to learn about the photon model of electromagnetic radiation and the use of electromagnetic radiation for collecting evidence about the universe or for generating images of the inside of a human body.

In the Measuring waves unit, pupils learnt about the measurable features of a wave, the relationship between them and the wave equation.

Electromagnetic waves

Physical activity and equipment requiring safe use

The angle of refraction is less than the angle of incidence.

The angle of refraction is greater than the angle of incidence.

When the ray crosses the boundary, it bends towards the normal.

When the ray crosses the boundary, it bends away from the normal.

The ray diagram shows the refraction of a light wave when it crosses a boundary between two materials. Which of these statements are correct for light at a boundary from air into a transparent block?

The angle of refraction is always smaller than the angle of incidence.

The greater the angle of incidence, the greater the angle of refraction.

When the angle of incidence doubles, the angle of refraction doubles.

The angle of refraction increases by the same amount as the angle of incidence.

A student measures the angle of incidence and the angle of refraction at a boundary from air into a transparent block. The table shows the results. Which of these statements are correct?

Which of these ray diagrams shows a possible path of a ray through a plastic block?

The wavelength is shorter in air than in glass.

The speed of light is higher in air than in glass.

As a wavefront crosses the boundary, the section that is in air travels faster.

The change in speed makes the wavefront rotate.

The diagram represents the refraction of a light wave as it passes from glass into air. It shows rays and wavefronts. Which of the statements are correct?

A light wave travels from a medium in which it is slower into a medium in which it is faster. The vertical black line shows the boundary between the two media. Which diagram is correct?

In a wavefront diagram, what does a wavefront show?

A ray box produces a single ray of light.

Light can only reflect from shiny surfaces.

loses its brightness as it passes through the object

In a ray diagram, the ray that approaches a surface or boundary is called the {{}} ray.

This ray diagram represents a light wave hitting a mirror. Which diagram shows the normal line drawn correctly (as a dashed line)?

The ray diagram represents a light wave reflecting from a mirror. A student has placed a protractor over the diagram. What is the angle of incidence?

Content guidance

Risk assessment required - equipment

Adult supervision required

This lesson will be removed by end of Summer Term 2025.

Refraction through a rectangular block (including wave front diagrams)

Lesson outcome

Content guidance

This lesson will be removed by end of Summer Term 2025.